T Association.Ismail et al. Journal of Cardiovascular Magnetic Resonance 2014, 16:49 http://jcmr-online.com/content/16/1/Page 5 ofFigure 2 Examples of results of pixel-wise quantitative CEP-37440 structure first-pass cardiovascular magnetic resonance perfusion imaging (ml/g/min) for (A) severe microvascular dysfunction and (B) non-severe patients. Stress images are shown on the top row and rest images on the bottom row for identical basal, mid-ventricular and apical PubMed ID:http://www.ncbi.nlm.nih.gov/pubmed/27735993 slices together with their corresponding pixel maps.(1.22 ?0.36 ml/g/min versus 1.39 ?0.34 ml/g/min, P < 0.001). After stress, whereas MBF rose significantly in the remote areas (1.39 ?0.34 ml/g/min rising to 2.60 ?0.57 ml/g/min, P < 0.001), stress MBF in hypoperfused ROI in patients with severe microvascular dysfunction not only failed to rise, but fell significantly from baseline values (1.22 ?0.36 ml/g/min falling to 1.05 ?0.39 ml/g/ min, P = 0.021). In contrast, for the non-severe patients(Figure 3B), there was a significant rise in mean MBF with stress, even in the hypoperfused areas (1.05 ?0.28 ml/g/ min rising to 1.87 ?0.45 ml/g/min, P < 0.001). ROI analysis in both groups showed significant hyperemic responses in regions remote from perfusion defects (1.39 ?0.34 ml/g/min rising to 2.60 ?0.57 ml/g/min, P < 0.001; and 1.20 ?0.31 ml/g/min rising to 2.74 ?0.85 ml/g/min, P < 0.001, respectively). The ratio of the minimum MPRITable 2 Baseline cardiovascular magnetic resonance findings for the study cohort stratified according to the presence/ absence of severe microvascular dysfunctionNon-severe CMR parameters ?n ( ) Maximum end-diastolic wall thickness ?mm LV-EDV index ?ml/m2 LV-ESV index ?ml/m2 LV ejection fraction ? LV mass index ?g/m2 24 (68.6) 18.9 ?4.5 68.5 ?15.1 19.5 ?7.9 72.0 ?8.3 93.6 ?24.9 Severe 11 (31.4) 22.2 ?4.0 64.3 ?10.5 17.2 ?6.1 73.8 ?6.5 103.4 ?30.0 All patients 35 19.9 ?4.6 67.2 ?13.8 18.8 ?7.4 72.5 ?7.7 96.7 ?26.6 P value 0.048 0.419 0.393 0.515 0.All values mean ?SD. CMR = Cardiovascular Magnetic Resonance; LV = Left Ventricular; EDV = End-diastolic volume; ESV = End-systolic volume.Ismail et al. Journal of Cardiovascular Magnetic Resonance 2014, 16:49 http://jcmr-online.com/content/16/1/Page 6 ofFigure 4 Myocardial perfusion reserve index (MPRI) in the severe and non-severe microvascular dysfunction groups for the most-hyperemic transmural segments, sub-epicardial, and sub-endocardial sub-sectors.MBF was significantly higher than epicardial MBF (1.25 ?0.35 ml/100 g/min versus 1.20 ?0.35 ml/g/min, P < 0.001) with an endocardial to epicardial MBF ratio of 1.05 ?0.11. However, at stress, this pattern was reversed with endocardial MBF increasing significantly less than epicardial MBF (2.00 ?0.76 ml/g/min versus 2.36 ?0.83 ml/g/min, P < 0.001) giving a ratio of 0.85 ?0.18. The more blunted hyperemic response in the endocardium relative to the epicardium was also reflected by a significantly lower mean MPRI (1.68 ?0.65 versus 2.06 ?0.73, P < 0.001 respectively).Figure 3 Mean myocardial blood flow (MBF) at rest and stress for hypoperfused and remote regions of myocardium for the (A) severe microvascular dysfunction and (B) non-severe patients.Perfusion and LV wall thicknessfor hypoperfused areas to the maximum MPRI in remote regions was significantly lower in the severe microvascular dysfunction patients at 0.31 ?0.10 versus 0.58 ?0.16 in the non-severe group (P < 0.001).Transmural distribution of blood flow in response to vasodilator stressThere was no significant relationsh.